Liquid medicaments or drugs have to be stored and transported by way of sealed containers, such like carpules, ampoules, vials or infusion bottles. Most of the known containers comprise a vitreous body made of a material being substantially inert to the medicament stored therein. Such storage units for liquid medicaments may also provide controlled and well-defined dispensing of the medicament provided therein. In particular with carpules or cartridges, a tubular or cylindrical vitreous barrel is sealed at one end by way of a piston slidably disposed in the barrel.
When applying thrust or pressure to the piston, e.g. in a distal direction, a pre-defined dose of the medicament can be expelled from the interior volume of such a container, provided that its opposite, hence distal outlet is coupled with or is in fluid-connection with e.g. a piercing assembly, like an injection needle.
There generally exists a large variety of different cartridges 10, 20, 30 as for instance depicted in FIGS. 1a, 1b and 1c. Depending on the type of the medicament stored therein and the particular application or administering scheme, the medicament should be administered or dispensed, the cartridges 10, 20, 30 comprise different filling volumes 16, 26, 36 and a rather large variety of peripheral geometries.
A standard cartridge 10 is for instance schematically depicted in FIG. 1a. This cartridge 10 comprises a vitreous tubular body 12 defining an inner volume 16 that can be filled with a medicament to be dispensed. At the upper, proximal end section, the cartridge 10 comprises a piston 14 being displaceable in distal direction towards the lower outlet end of the cartridge 10.
In comparison to the cartridge 10 according to FIG. 1a, FIG. 1b illustrates another cartridge 20 having a barrel 22 being smaller in diameter. However, axial elongation of cartridges 10, 20 and of their respective vitreous barrels 12, 22 is substantially identical. Also the axial size of the pistons 14, 24 is substantially the same. As a consequence, a pressure receiving or proximal end face 18, 28 of the respective pistons 14, 24 of the cartridges 10, 20 as depicted in FIGS. 1a and 1b is located at the same position relative to the respective barrel 12, 22.
In fact, the available filling volume 26 of cartridge 20 is much smaller than the filling volume 16 of cartridge 10.
In FIG. 1c, another common type of a cartridge 30 is illustrated. In comparison with cartridge 10 as depicted in FIG. 1a, the cartridge 30 comprises a reduced axial length but its barrel 32 features a diameter being substantially comparable to the diameter of the barrel 12. Even though the geometry and shape of the cartridges 20, 30 drastically differs, their available filling volume 26, 36 may be in the same range. Due to the reduced length, the proximal end face 38 of the piston 34 of the cartridge 30 drastically differs from the positions of the proximal end faces 18, 28 of the cartridges 10, 20 as shown in FIGS. 1a and 1b. 
Since drug delivery devices, such like pen-type injectors making use of such cartridges 10, 20, 30 are produced in a mass production environment, the large variety of cartridge volumes and cartridge geometries provides an undue burden for the manufacturing of the device and/or for a filling process of such cartridges. Hence, for different filling volumes of various cartridges 10, 20, 30 different types of barrels 12, 22, 32 and pistons of variable size 14, 24, 34 have to be ordered, stored and supplied to the respective assembly or filling line.
Moreover, when cartridges of different size are to be filled with a medicament, a respective filling or assembly line for the cartridges must be reconfigured. The geometric variance and the large spectrum of cartridge sizes and shapes therefore comes along with various drawbacks for a mass production process. Moreover, repeated reconfiguration of a mass production process is always accompanied with rising costs and with a decreased occupancy of generally available production or filling lines.
It is therefore an object of the present invention to provide a cartridge design by way of which the above mentioned drawbacks can be substantially set aside. The invention focuses on a smooth and easy as well as on a cost-efficient solution to provide a variety of cartridges having different filling volumes. The invention particularly focuses on a cost-efficient implementation in a mass production process and intends to reduce tooling times for automated assembly- and filling lines as well as to reduce costs for manufacture and transport of cartridges.